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United States Patent | 5,610,954 |
Miyashita ,   et al. | March 11, 1997 |
A clock reproduction circuit produces a data clock from a data signal. The clock reproduction circuit includes a voltage controlled oscillator, a phase detector, a frequency error detection circuit and a charge pump whose output is controlled by the outputs of the phase detector and the frequency error detection circuit. A VCO clock output from the voltage controlled oscillator is synchronized with the data clock by the feedback loop consisting of these elements. The frequency error detection circuit detects a frequency error between the VCO clock and the data clock by detecting changes in the phases of the VCO clock at the transition edges of the data signal. Analog and digital frequency error detection circuits are used. Further, improved circuit elements in the clock reproduction circuit used.
Inventors: | Miyashita; Takumi (Kawasaki, JP); Tomesakai; Nobuaki (Kawasaki, JP) |
Assignee: | Fujitsu Limited (Kawasaki, JP) |
Appl. No.: | 401793 |
Filed: | March 10, 1995 |
Mar 11, 1994[JP] | 6-041054 | |
Mar 17, 1994[JP] | 6-047145 | |
Sep 14, 1994[JP] | 6-220385 | |
Dec 01, 1994[JP] | 6-329597 | |
Jan 10, 1995[JP] | 7-002232 |
Current U.S. Class: | 375/375; 327/157; 331/25; 375/374 |
Intern'l Class: | H03D 003/24 |
Field of Search: | 375/373,374,375,376 331/1 R,1 A,14,17,18,25,34 327/156,157 |
4773085 | Sep., 1988 | Gordell | 375/376. |
4780844 | Oct., 1988 | Keller | 375/376. |
4803705 | Feb., 1989 | Gillingham et al. | 331/1. |
5027085 | Jun., 1991 | DeVito. | |
5173617 | Dec., 1992 | Alsup et al. | 375/373. |
5455540 | Oct., 1995 | Williams | 331/1. |
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